Ebook cover size checker and resizer for KDP, Apple Books, Kobo and Gumroad
Amazon KDP recommends an ebook cover 2,560 pixels high by 1,600 wide, in JPEG, and refuses one over 50 MB. Apple Books, Kobo and Gumroad each have rules of their own. Choose your image to check it against all four and save a copy at the size each one wants; the file never leaves your browser.
Ebook cover checker and resizer
Runs in your browser. Nothing you enter is uploaded.
Choose an image to check it against every store and make a copy at the size you pick.
Chapbook designs every book’s cover at KDP’s 1,600 × 2,560 pixels. It becomes the start of a brief; nothing runs until you choose Generate.
Checked against KDP, Apple Books, Kobo Writing Life and Gumroad on 29 October 2026.
Cover rules by store
Read on each store’s own help page on 29 October 2026; Amazon KDP’s on 29 October 2026. A required rule fails the upload; a recommended one is the store’s advice.
| Store | Rule | Required or advice |
|---|---|---|
| Amazon KDP Kindle eBook cover | JPEG, PNG, GIF (non-animated) or TIFF | Required |
| At least 500 pixels on the longest side | Required | |
| 10,000 pixels or fewer on each side | Required | |
| At most 50 MB | Required | |
| The shape of 2,560 pixels in height x 1,600 pixels in width | Recommended | |
| 2,500 pixels high or more, for high-definition screens | Recommended | |
| JPEG is the preferred format | Recommended | |
| Apple Books Book cover art | PNG or JPEG format | Required |
| At least 1,400 pixels on its shortest side | Required | |
| Kobo Writing Life eBook cover | A .jpg or .png file | Required |
| No larger than 5 MB | Recommended | |
| The shape of the standard Kobo eReader’s 1448 by 1072 screen | Recommended | |
| Gumroad Product page cover | A PNG, JPEG or GIF image | Required |
| Smaller than 50 MB | Required | |
| The shape of 1280 pixels wide x 720 pixels tall, as a rule of thumb; a tall cover is shown at its own shape | Recommended | |
| Gumroad Optional thumbnail (library, Discover, profile) | At least 600 x 600 pixels | Recommended |
| Square, as the thumbnail shows | Recommended |
What it checks
For each store, the checker reads four things from your file: its width and height in pixels, its shape, its size on disk and its format. A required rule is one the store’s own page says an upload fails without. A recommended one is the store’s advice, which a file can miss and still upload.
One thing it cannot read from the file is its colour mode: Apple asks for RGB, and KDP recommends it. Check that in the program you made the cover in.
How the resizer fits a cover
Pick a store and the resizer makes a JPEG at that store’s size. Crop scales the image until it fills the size and trims what is left over evenly from both sides. Pad scales it until it fits whole and fills the bands with a colour, which starts as the average of your image’s edge so the bands read as its own ground. If the store limits the file size, the JPEG’s quality is lowered only as far as the limit needs.
If the image has to be enlarged to fit, the resizer says so: an enlarged cover looks softer, and a larger original is better.
